Chip packaging is often intensely involved with heat removal. Thermal expansion-mismatch challenges exist between the die, the underfill material, and the substrate to which the die is mounted. The thermal mismatch often is exhibited at the joint of a solder bump and a bond pad.
One method of dealing with solder bump stress is to encapsulate the solder bumps at the comers with an underfill layer. This method only encapsulates solder bumps at the periphery of the package. It does not encapsulate the solder bumps at the center of the component.
With the dispensing and printing of stress-compensation layer materials on the package among the array of solder bumps, solder bump contamination is a concern.